1. Field of the Invention
This invention relates to emergency call systems (e.g., E9-1-1), including wireless and Internet Protocol (IP) based Voice Over Internet Protocol (VoIP) emergency call systems.
2. Background of the Related Art
9-1-1 is a phone number widely recognized in North America as an emergency phone number that is used to contact emergency dispatch personnel. Enhanced 9-1-1 (E9-1-1) is defined by an emergency call being selectively routed to an appropriate PSAP, based upon the caller's phone number (ANI) or special identifier (P-ANI, or “Pseudo Automatic Number Identifier”, also referred to as “ESxK”), and includes the transmission of callback number and location information to the call taker. E9-1-1 may be implemented for landline, cellular or VoIP networks. Regardless of the network type, a 9-1-1 service becomes E-9-1-1 when automatic number identification and automatic location information related to the call is provided to the 9-1-1 operator at the PSAP.
A Public Service Answering Point (PSAP) is a dispatch office that receives 9-1-1 calls from the public. A PSAP may be a local, fire or police department, an ambulance service or a regional office covering all services. In some cases, typically in situations in which the intended PSAP cannot be accessed due to infrastructure failure or overflow, 911 calls may be routed to an Emergency Call Center (ECC). As used herein, the term “PSAP” refers to either a public safety access point (PSAP), or to an Emergency Call Center (ECC).
PSAPs typically acquire callers' location information via an automatic location identifier (ALI) database. FIG. 4 shows a conventional landline (PSAP) to (ALI) connection.
In particular, FIG. 4 shows a PSAP 400 connected to one Automatic Location Identifier (ALI) database 401. An ALI is a database that accepts a PSAP query with telephone number, relates the telephone number to an address and provides that address (location information) back to the PSAP in a manner that works for the customer premise equipment (CPE) display. An ALI is typically owned by the PSAP's System Service Provider (SSP, typically a LEC) or by the PSAP itself, and may be regional (i.e. connected to many PSAPs) or standalone (i.e. connected to only one PSAP). There is a standard interface protocol for PSAP-ALI connection/communication, although each PSAP typically customizes the data presentation on their CPE.
Upon receiving a 9-1-1 call, the PSAP 400 queries the ALI 401 for location data. The ALI database 401 accepts the query from the PSAP 400 for location. The query includes the telephone number of an emergency caller. The ALI database 401 relates the received telephone number to a physical street address and provides that street address (location information) back to the PSAP 400 in a manner that works for the customer premise equipment (CPE) display at the PSAP 400.
Most PSAPs are publicly funded and maintain only one outside ALI connection for both landline and non-landline networks. Regional ALIs can support numerous PSAPs. Most ALIs also support one or more connections to other ALIs. Some ALIs (usually those owned and operated by individual PSAPs) are able to support only one outside connection to another ALI. External ALIs are usually operated and maintained by a positioning center. Positioning centers typically exist to support E911 solutions for VoIP (VPC) or mobile (MPC) carriers.
FIG. 5 shows a context diagram for a conventional non-landline positioning center (e.g., a VoIP or wireless positioning center, xPC).
In particular, the ALI database 401a includes a conventional pANI (ESQK or ESRK) in a location request sent to an appropriate positioning center 402 (XPC). The emergency services key (ESQK or ESRK) is used, by the positioning center 402 in lieu of a telephone number (ANI) to look up the location and other call information associated with the emergency call.
In non-landline telephony, the PSAPs 400a query the ALI 401a for location information. However, the ALI 401a is not pre-provisioned with location data for non-landline calls (e.g. cellular, VoIP etc) and must communicate with other network entities to obtain and deliver location data to the PSAP 400a. 
Non-landline telephony standards (e.g. cellular, VoIP etc) have mandated that ALIs 401a maintain connectivity to a positioning center 402 that is able to provide current location data for a non-landline call. In the current state of technology, the positioning center 402 provides the caller's location and the callback number to the ALI, which passes it to the requesting PSAP. An ALI may maintain connectivity to more than one positioning center. An XPC may also be connected to multiple ALIs. Multiple interface types exist to support these connections—both standard and non-standard (e.g. NENA-02, E2/E2+/V−E2(ESP), PAM, etc.). The ALI typically establishes the interface protocol, while the XPC must accommodate that protocol. Thus XPCs typically support multiple interface protocols, the ALIs support only one.
Whether landline or non-landline, conventional emergency call centers, e.g., public safety access points (PSAPs) 400a, use emergency services keys to query for location information. Technically, these keys are categorized as ANI or pANI. ANI are used with wireline 911 calls, and consist simply of the callers landline telephone number. pANI and used for non-wireline calls. Emergency services query keys (ESQK) or an emergency services routing keys (ESRK), collectively referred to herein as ESxK, are both forms of pANI. Although their functions are identical, ESQKs are used for VoIP calls while ESRKs are used for wireless (cellular) calls.
An emergency service key is associated with a particular selective router 417a associated with a given public safety access point (PSAP) 400a. The emergency services keys ESQK and ESRK are conventionally used to query the automatic location identification (ALI) database 401 for the location of a given emergency caller. An emergency services key is delivered via the voice call path to the E9-1-1 selective router 417a. The emergency services key is used by a selective router 417a as a key to determine which PSAP should receive the call. The emergency services key is delivered by the selective router 417a to a PSAP 400a as the calling number/ANI for the emergency call, and is subsequently used by the PSAP 400a to request automatic location information (ALI) information indicating the location of the device making the emergency call. Conventional emergency service keys conform to ten-digit North American Numbering Plan Number definitions and they may or may not be dialable.
Voice-Over-Internet Protocol (VoIP) is a technology that emulates a phone call, but instead of using a circuit based system such as the telephone network, utilizes packetized data transmission techniques most notably implemented in the Internet. 911 calls made using VoIP technology must reach the correct PSAP, but there currently is no uniform interface to the various PSAPs for call delivery because the technology for connecting calls varies. For instance, not all PSAPs are Internet Protocol (IP) capable. Some PSAPs are accessed via ordinary public switched telephone network (PSTN) telephone lines. Some PSAPs are accessed through selective routing such as direct trunks. Still other PSAPs are accessed using IP connections. There is no uniformity among the thousands of different PSAPs for receiving VoIP calls.
Moreover, some Public Safety Access Points (PSAPs) are not enhanced, and thus do not receive the callback or location information at all from any phone, landline or wireless.
The use of VoIP technology is growing quickly. As people adopt voice-over-IP (VoIP) technology for routine communications, the inventors herein recognize that there is a growing need to access E911 services including provision of location information from a VoIP device.
The existing E911 infrastructure is built upon copper wire line voice technology and is not fully compatible with VoIP. Given VoIP technology, there are at least three VoIP scenarios:                1. A VoIP UA that is physically connected to a static data cable at a “home” address. For instance, an Analog Telephone Adapter (ATA) that is connected to the “home” data cable and uses traditional telephone devices. This scenario is defined as “static” VoIP.        2. A VoIP UA that is physically connected to a data cable at a location different than its “home” address. For instance, a laptop computer device utilized away from home as a VoIP software telephone would be a VoIP ‘visitor’ device as described by this scenario. This scenario is defined as “nomadic” VoIP.        3. A VoIP UA that is wireless, physically disconnected from any data cable. In this situation, the VoIP UA connects to the VoIP service provider via either a wide-area wireless technology (e.g., cellular, PCS, WiMAX) or via a local-area wireless technology (e.g., Wireless Fidelity (WiFi), UWB, etc.) using a laptop computer or handheld device. This scenario is defined as “mobile”, although the distinction between VoIP and wireless are blurred.        
VoIP phone calls are routed to a VoIP voice gateway, from which they are passed on to their destination. A VoIP voice gateway or soft switch is a programmable network switch that can process the signaling for all types of packet protocols. Also known as a ‘media gateway controller,’ ‘call agent,’ or ‘call server’, such devices are used by carriers that support converged communications services by integrating SS7 telephone signaling with packet networks. Softswitches can support, e.g., IP, DSL, ATM and frame relay.
The challenges evident with respect to determining the location of a calling VoIP telephone is perhaps most evident with respect to its use to make an emergency call (e.g., a 911 call). Nevertheless, VoIP telephone technology is quickly replacing conventional switched telephone technology. However, because VoIP is Internet Protocol (IP) based, call related information such as CallerID type services may not be available or accurate. A location of a given VoIP device may be manually provisioned to be at a given geographic location, or queried from a home location register (HLR) in a mobile system. Technologies for automatically locating VoIP devices are in their infancy.
In addition, some Public Safety Access Points (PSAPs) are not enhanced, and thus do not receive the callback or location information at all from any phone; landline, cellular or VoIP.
Moreover, there is complexity in public access to Public Safety Answering Points due to lack of a Session Initiation Protocol (SIP) Uniform Resource Identifier (URI) for all PSAPs. (SIP is the IP-based protocol defined in IETF RFCs 3261 and 2543.) SIP is one of two dominant protocols used by the VoIP industry. URI is the addressing technology for identifying resources on the Internet or a private intranet. URIs were originally defined as two types: Uniform Resource Locators (URLs) which are addresses with network location, and Uniform Resource Names (URNs) which are persistent names that are address independent. Today, a URI is defined by its purpose rather than the URL vs. URN classification.) Some PSAPs are accessed only by conventional telephone line, others only by direct telephone trunk lines. Not all PSAPs are accessible via the Internet.
FIG. 6 shows basic conventional VoIP elements required to interconnect a VoIP emergency E911 caller to a relevant public safety access point (PSAP).
In particular, as shown in FIG. 6, VoIP telephone devices 102a and 102b, (collectively referred to as 102) are connected to respective VoIP Service Provider (VSP) soft switches 104a, and 104b, (collectively referred to as 104) using an Internet Protocol (IP) connection, most commonly over the Internet. The VoIP service provider's soft switch 104 in turn communicates with a respective VoIP Positioning Center (VPC) 106a, 106b, (collectively referred to as 106) using an appropriate IP connection. Each VSP requires use of their own VPC, as depicted in FIG. 5.
FIG. 7 shows in more detail conventional VoIP elements required by a VPC to interconnect a VoIP emergency E911 caller to a relevant public safety access point (PSAP).
In particular, as shown in FIG. 7, each VPC 106 comprises its own respective route determination module 404, call delivery module 406, and provisioning list 408.
A respective location information server (LIS) 108 services each of the VPCs 106. The LIS 108 is responsible for storing and providing access to the subscriber location information needed for E9-1-1 call processing (as defined by the NENA VoIP Location Working Group).
A conventional VoIP Positioning Center (VPC) 106 is a system that attempts to determine the appropriate or correct PSAP 114 that a VoIP emergency E911 call should be routed to based on the VoIP subscriber's position. The conventional VPC 106 also returns associated routing instructions to the VoIP network. The conventional VPC 106 additionally provides the caller's location and the callback number to the relevant PSAP through the automatic location identifier (ALI) (The ALI is a database that accepts a PSAP query, and using that relates a specific telephone number to a street address. In the case of an Emergency Services Query Key (ESQK), the ALI database steers the query to the appropriate VPC and steers the response back to the PSAP. An ALI is typically owned by a LEC or a PSAP.)
Further as shown in FIG. 7, each VSP routes the emergency 9-1-1 call, without location object added, to their VPC 106. The VPC must determine the correct PSAP 114 (collectively represented by PSAP 114a, 114b and 114c) and route to it using the appropriate technology.
In a first scenario, the VPC 106 passes the 9-1-1 call to the PSAP 114a using an INVITE telephone number message, via a media gateway 110 that translates between the IP protocol of the INVITE message and a telephone line interface, and interfaces with the public switched telephone network (PSTN) 112.
In a second scenario, the VPC 106 passes the 9-1-1 call to the PSAP 114b using an INVITE S/R message, via an Emergency Services Gateway (ESGW) 120 and selective router 122. An ESGW is a media gateway dedicated to E911 and connected to the Selective Router (S/R) via direct trunks. In this scenario, the selective router 122 is connected to the relevant PSAP 114b via direct trunks.
In a third scenario, the VPC 106 passes the 9-1-1 call to the PSAP 114c using an INVITE PSAP message, via IP, to the PSAP 114c. In the second and third scenario, the ALI 126 must be inter-connected with each VPC 106 (a,b). Furthermore, each VPC is burdened with supporting all the various ALI protocols: ve2, e2, PAM, legacy NENA, etc.
Thus, most Public Safety Answering Points (PSAPs) receive 911 calls via designated voice and data circuits called the “E911 network” that are not accessible via the Public Switched Telephone Network (PSTN). Network elements include a selective router and dedicated circuits between that router and the PSAP. Access to the selective router is via dedicated circuits between the ESGW and the S/R. As a result, the selective router cannot be directly accessed via the PSTN. Moreover, the amount of data that can be forwarded to the PSAP is extremely limited and ASCII data based.
There is a need for a method and technology allowing broader data based services in an E911 system.